In embedding wire ties in mortar joints, how far off the recommended amount can a contractor be? We're spacing wire ties 16 inches o.c. vertically and 2 feet o.c. horizontally in a one-story utility brick veneer. We're embedding the ties 1 1/2 to 1 3/4 inches. How do we show that 1/4-inch variation is adequate? What test procedure do we use to determine pullout strength, and what should the minimum pullout strength be?
In Technical Note 44B, "Wall Ties for Brick Masonry," the Brick Institute of America (BIA) recommends that the outside edge of the tie be no closer than 5/8 inch from the outside face of the brick nor farther than half the brick depth from the outside face. For a typical 3 5/8-inch-deep brick, this translates to an embedment of 1 3/4 to 3 inches. To protect ties from corrosion, it generally is better to keep the outside edge of the ties as far away from the outside face of the wall as possible. If the ties are embedded less than half the brick depth, however, pullout strength may not be adequate. If ties are embedded less than this, they should be tested in accordance with ASTM E 754, Test Method for Pullout Resistance of Ties and Anchors Embedded in Masonry Mortar Joints. The pullout strength of the ties should be at least four times the design load on the ties determined by the structural engineer on the project.